Virtual reality (VR) offers an unprecedented opportunity to study behavior and brain activation in situations much more closely approximating real-life than most laboratory or treatment situations. By immersing subjects in realistic-looking, dynamic, interactive, individualized environments, it is possible to provide stimulus cues of the experimenter's choosing and timing to elicit more intense and controlled reactions from subjects. Our goal is to provide a flexible tool for drug-abuse researchers interested in using virtual reality simulations for neurobehavioral studies, especially in the context of fMRI studies. Our Phase I research has demonstrated that VR can provoke strong cravings in cigarette smokers, both on a subjective rating scale and in brain areas controlling emotional and cognitive responses. We identified a range of stimuli that evoke effective craving. The size of the craving response was as great as that typically reported in the literature, even for in vivo studies. We learned that the strongest cravings can be very specific and idiosyncratic and can be strongly influenced by the dynamics of the environment. In Phase II we intend to use similar behavioral and fMRI techniques to study cravings in larger groups of smokers, alcohol abusers and cocaine abusers and will compare the responses to more standard techniques. A user-friendly interface will be developed that will allow therapists to develop individualized VR worlds directed at the patient as a component of cognitive-behavioral treatment sessions. Physiological monitoring will be added to allow biofeedback to modulate certain aspects of the simulation, either in or out of the MR scanner. This effort will provide the research foundation to support four novel systems targeted to study and treat addiction: 1) a VR brain-imaging research package; 2) a desktop VR-addiction research package; 3) a desktop VR-addiction treatment package; and 4) a VR brain imaging clinical package. This new methodology has the potential to improve the lives of millions of smokers, alcoholics and cocaine addicts through more effective research and treatment strategies.